Through analyzing the essence of the IoT and the hiberarchy architecture in it, some security risks, security request and security ways for the risks are discussed. The possible technique at each layer and its advantage or disadvantage is studied respectively. The extremely characteristics of the perception layer are summarized, based on it, a PKI-like security mechanism including PKI-like security foundation architecture and PKI-like protocol are presented in this paper, and the characteristics and its application domain are summarized to present. A couple of new research directions are proposed. After some further improvement research on it, which maybe a hot topic in the near future.